Merge pull request #948 from effigies/mnt/deprecate_setattr_on_read

MNT: Officially deprecate onetime.setattr_on_read

Author: effigies

nibabel/nicom/dicomwrappers.py

@@ -20,7 +20,7 @@
 from . import csareader as csar
 from .dwiparams import B2q, nearest_pos_semi_def, q2bg
 from ..openers import ImageOpener
-from ..onetime import setattr_on_read as one_time
+from ..onetime import auto_attr as one_time
 from ..pydicom_compat import tag_for_keyword, Sequence
 from ..deprecated import deprecate_with_version
 

nibabel/onetime.py

@@ -15,11 +15,13 @@
 References
 ----------
 [1] How-To Guide for Descriptors, Raymond
-Hettinger. http://users.rcn.com/python/download/Descriptor.htm
+Hettinger. https://docs.python.org/howto/descriptor.html
 
 [2] Python data model, https://docs.python.org/reference/datamodel.html
 """
 
+from nibabel.deprecated import deprecate_with_version
+
 # -----------------------------------------------------------------------------
 # Classes and Functions
 # -----------------------------------------------------------------------------
@@ -176,4 +178,6 @@ def auto_attr(func):
 # -----------------------------------------------------------------------------
 
 # For backwards compatibility
-setattr_on_read = auto_attr
+setattr_on_read = deprecate_with_version(
+    message="setattr_on_read has been renamed to auto_attr. Please use nibabel.onetime.auto_attr",
+    since="3.2", until="5.0")(auto_attr)

nibabel/tests/test_onetime.py

@@ -0,0 +1,17 @@
+import pytest
+from nibabel.onetime import auto_attr, setattr_on_read
+
+
+def test_setattr_on_read():
+    with pytest.deprecated_call():
+        class MagicProp:
+            @setattr_on_read
+            def a(self):
+                return object()
+
+    x = MagicProp()
+    assert 'a' not in x.__dict__
+    obj = x.a
+    assert 'a' in x.__dict__
+    # Each call to object() produces a unique object. Verify we get the same one every time.
+    assert x.a is obj

nibabel/tests/test_removalschedule.py

@@ -12,7 +12,8 @@
 ]
 
 OBJECT_SCHEDULE = [
-    ("5.0.0", [("nibabel.pydicom_compat", "dicom_test")]),
+    ("5.0.0", [("nibabel.pydicom_compat", "dicom_test"),
+               ("nibabel.onetime", "setattr_on_read")]),
     ("3.0.0", [("nibabel.testing", "catch_warn_reset")]),
     # Verify that the test will be quiet if the schedule outlives the modules
     ("1.0.0", [("nibabel.nosuchmod", "anyobj"), ("nibabel.nifti1", "nosuchobj")]),